Many Christmas lights that are sold for use outdoors are in fact not suitable for our damp Irish climate, a lighting expert has warned.

As homeowners around the country get ready to festoon their houses with colourful lights, Gabriel Byrne of Fantasy Lights said a combination of unsuitable outdoor lights and safety shortcuts could prove lethal.

"Many of the lights being sold in Ireland are marked for both indoor and outdoor use - which leads people to think that they are safe for both," said Mr Byrne.

"However, not only are these lights and decorations usually unsuitable for our climate, in many cases they represent a real danger to the user if the transformer is plugged in out of doors.

"The rule of thumb for outdoor lighting is if there are pins on the plugs, keep them indoors.

"If you are using outdoor lighting, then you must use specific low-voltage outdoor transformers, which are weatherproof, IP-rated, hardwired, and use rubberised cables."

Mr Byrne founded Fantasy Lights more than 30 years ago, and has been responsible for lighting up thousands of houses. He warned against taking shortcuts.

"A lot of electrical issues arise when people connect different lighting sets together, and we would ask householders to make sure that your lights are from the same manufacturer and are of the same quality and standard," he said.

"While we use weatherproof connections on all of our joints, I shudder sometimes when I see some of the chances people take with electricity when it comes close to the festive season.

"I have seen instances of people putting transformers and extension cables in plastic bags to shield them from the elements, which is extremely dangerous when dealing with what is high-voltage electricity in a damp environment."